Hair fall is a physiological phenomenon due to the natural course of life of a hair. Lack of sleep can cause hair fall but if you are sleeping for 7-8 hours daily then it is unlikely to be the culprit. So, the causes for excessive hair fall may be physiological or pathological and include hormonal changes, fungal infection, physical effects (traction, heat, chemicals), psychological & stress-related reasons, thyroid disorders, iron deficiency anemia, excessive intake of Vitamin A, hereditary reasons etc. I suggest you to take opinion of a Dermatologist who will do a methodical medical check-up and advice accordingly.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
Thank you for your help. I think I have found out the reason of my hair fall.